Laser irradiation method, laser irradiation apparatus, and semiconductor device

ABSTRACT

An object of the present invention is obtaining a semiconductor film with uniform characteristics by improving irradiation variations of the semiconductor film. The irradiation variations are generated due to scanning while irradiating with a linear laser beam of the pulse emission. At a laser crystallization step of irradiating a semiconductor film with a laser light, a continuous light emission excimer laser emission device is used as a laser light source. For example, in a method of fabricating an active matrix type liquid crystal display device, a continuous light emission excimer laser beam is irradiated to a semiconductor film, which is processed to be a linear shape, while scanning in a vertical direction to the linear direction. Therefore, more uniform crystallization can be performed because irradiation marks can be avoided by a conventional pulse laser.

This application is a continuation of U.S. application Ser. No.10/315,779 filed on Dec. 10, 2002 now U.S. Pat. No. 6,944,195 which is acontinuation of U.S. application Ser. No. 09/500,247 filed on Feb. 8,2000 (now U.S. Pat. No. 6,535,535 issued Mar. 18, 2003).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device having a circuitstructured with a thin film transistor. For example, it relates to thestructure of an electro-optical device, typically a liquid crystaldisplay device, and of an electric equipment loaded with such anelectro-optical device as a component. Note that throughout thisspecification, the semiconductor device indicates general devices thatmay function by use of semiconductor characteristics, and that the abovestated electro-optical device and electric equipment are categorized asthe semiconductor device.

2. Description of the Related Art

In recent years, the technique of crystallizing and improving thecrystallinity of an amorphous semiconductor film or a crystallinesemiconductor film (a semiconductor film having crystallinity which ispolycrystalline or microcrystalline, but is not a single crystal), inother words a non-single crystal semiconductor film, formed on aninsulating substrate such as a glass, has been widely researched.Silicon film is often used as the above semiconductor film.

Comparing a glass substrate with a quartz substrate, which is often usedconventionally, the glass substrate has the advantages of low cost andgood workability, and can be easily formed into a large surface areasubstrate. This is why the above research is performed. In addition, thereason for preferably using a laser for crystallization is that themelting point of a glass substrate is low. High energy can be impartedto a non-single crystal film be means of a laser without causing muchchange in the temperature of the substrate.

A crystalline silicon film formed by performing laser annealing has ahigh mobility. Accordingly, it is actively used in monolithic typeliquid crystal electro-optical devices, where thin film transistors(TFTs) are formed using this crystalline silicon film, for example, TFTsfor driving pixels and for driver circuits, are formed on one glasssubstrate. The crystalline silicon film is formed from many crystalgrains. Therefore, it is called a polycrystal silicon film or apolycrystal semiconductor film.

Further, a method of performing laser annealing by processing a highoutput pulse laser beam, such as an excimer laser by means of opticalsystem, into a square spot of several centimeters, or into a linearshape with a length of 10 cm or more, on the surface to be irradiated,and scanning the laser beam (the laser beam irradiation position ismoved relatively to the surface to be irradiated), has been preferablyused because it has good mass productivity and is superior industrially.In addition, continuous emission lasers with very high output, such asan Ar laser, have been recently developed. There are reports of goodresults obtained when using a continuous emission laser for annealing asemiconductor film.

In particular, if a linear shape laser beam is used, then a high degreeof mass productivity can be obtained because unlike the case of using aspot shape laser beam with which it is necessary to scan forward, back,left, and right, laser irradiation can be performed over the entiresurface to be irradiated by scanning only at a right angle to thelongitudinal direction of the linear shape laser. This is becausescanning at a right angle to the longitudinal direction is the mostefficient scanning direction. Due to this high mass productivity, thepresent use in laser annealing of a linear shape laser beam in which apulse emission excimer laser beam is processed into a suitable opticalsystem, is becoming a mainstream.

For the case of processing the above pulse emission excimer laser beaminto a linear shape and irradiating the linear shape laser beam whilescanning, for example, with a non-single crystal silicon film, thephenomenon of stripes at a portion where the beams overlap isnoticeable. (Refer to FIG. 22A.)

The semiconductor characteristics of the film differ remarkably for eachof these stripes, so if this striped film is used when forming anintegrated driver and pixel (system on panel) liquid crystal displaydevice, a drawback develops where these stipes appear on the screen, asis. The stripes which appear on the screen are caused by the non-uniformcrystallinity in both the driver section and the pixel portion. Thisproblem is being remedied by improving the film quality of thenon-single crystal silicon film, the laser irradiation object, but thisis not yet enough.

SUMMARY OF THE INVENTION

An object of the present invention is to solve this problem. The causeof the striped pattern is the energy diffusion in the width directionnear the edges of the linear shape laser beam. In general, when a linearshape laser beam is formed, an optical system called a beam homogenizeris used to make the beam homogenous. A beam so processed has a very highhomogeneity.

However, with respect to the light quality, there is a region in whichthe energy is gradually attenuated on the linear shape laser beam edge.The crystallinity of a semiconductor film irradiated with this region ispoor relative to a region exposed to the center of the beam. A method isthen taken of increasing the crystallinity of the regions in whichcrystallinity is poor by overlapping irradiation while graduallydisplacing the linear shape laser beam in the width direction of thebeam.

The most suitable overlap pitch has been found by experiment of theinventors of the present invention to be approximately one tenth of thebeam breadth (half width). Thus the crystallinity of the above regionwith poor crystallinity is improved. In the above example, the half linewidth is 0.6 mm, so laser irradiation is performed with an excimer laserpulse frequency of 30 Hz at a scanning velocity of 1.8 mm/s. The energydensity of the laser at this time is 380 mJ/cm². The methods stated tothis point are very general methods of using a linear shape laser tocrystallize a semiconductor film.

Continuous light excimer emission laser devices have been developedrecently. In order to promote the excitation of an emission gas,microwaves are used in this laser. By irradiating the emission gas withgigahertz order microwaves, the rate determining reaction of theemission is promoted. Thus the development of the continuous emissionexcimer laser, which has been not available, becomes possible.

The advantage of using an excimer laser for crystallization of a siliconfilm is the high absorption coefficient of an excimer laser for asilicon film. The absorption coefficient for a silicon film of acontinuous emission argon laser having a wavelength of approximately 500nm, the wavelength often used in crystallization of a silicon film, ison the order of 10⁵/cm. The intensity of an argon laser is attenuated to1/e (where e is the natural logarithm) at the point where it hastransmitted 100 nm of the silicon film. However, an excimer laser has anabsorption coefficient on the order of 10⁶/cm, one order of magnitudehigher, so its intensity is attenuated to 1/e at the point where it hastransmitted 10 nm of the silicon film.

In general, it is suitable for the thickness of a silicon film, whichbecomes a semiconductor element material, formed on a glass substrate tobe approximately 50 nm. If the silicon film is thicker than 50 nm, thereis a tendency for the off characteristics to become poor, while athinner film influences the reliability.

However, when a 50 nm silicon film is irradiated with an argon laser,over half of the argon laser light goes through the silicon film and isirradiated on the glass substrate. The glass substrate, which one doesnot want to be heated due to its melting point, is thus heated more thannecessary. In practice, when attempting crystallization by argon laserof a 200 nm silicon oxide film and a 50 nm silicon film formed in orderon a Corning 1737 substrate, the glass changes shape before there issufficient crystallization.

On the other hand, in the case of irradiation by an excimer laser,almost all of the light energy is absorbed in the 50 nm silicon film.Therefore nearly all of the excimer laser light can be used incrystallizing the silicon film.

Considering the above, use of an excimer laser for crystallization of asilicon film is good. An excimer laser, with a high absorptioncoefficient in a silicon film, is becoming more and more important forcrystallizing a semiconductor film because continuous emission typeshave become available.

Provided that a continuous emission excimer laser is used, the pulselaser irradiation marks do not form, which is the subject of the presentinvention. Therefore a film with very high homogeneity can be obtained.

The undulations of a silicon film formed by pulse laser irradiation areshown in FIGS. 22A to 22C, while the undulations of a silicon filmformed by continuous emission laser irradiation are shown in FIG. 1A to1C.

A diagram, as seen from above, of a silicon film irradiated by scanninga conventional pulse emission excimer laser is shown in FIG. 22A. FIG.22B is a cross sectional diagram of a cross section cut parallel to thescanning direction of the pulse emission excimer laser (in the verticalface of the silicon film which includes the line segment EF). Inaddition, FIG. 22C is a cross sectional diagram of a cross section of avertical face of the silicon film face at a right angle to the abovecross section (in the vertical face in the silicon film which includesthe line segment GH).

As can be understood from FIG. 22B, undulations of the same order as thesilicon film thickness have developed in the pulse laser irradiationmarks. On the other hand, the undulations shown in FIG. 22C are occurreddue to the energy non-uniformity in the longitudinal direction of thelinear shape laser beam, and compared to the undulations of FIG. 22B,are very small.

The diagram shown in FIG. 1A is a view seen from above of a silicon filmirradiated while scanning a continuous emission excimer laser. FIG. 1Bis a cross sectional diagram of a cross section cut parallel to thescanning direction of the continuous emission excimer laser (in thevertical face of the silicon film which includes the line segment AB).In addition, FIG. 1C is a cross sectional diagram of a cross section ofa vertical face of the silicon film face at a right angle to the abovecross section (in the vertical face in the silicon film which includesthe line segment CD).

As can be understood from at FIG. 1B, the irradiation marks of thecontinuous emission excimer laser can be nearly disregarded whencompared with the irradiation marks of the pulse laser. On the otherhand, the undulations shown in FIG. 1C are occurred due to the energynon-uniformity in the longitudinal direction of the linear shape laserbeam.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are diagrams showing a surface of a silicon film lasercrystallized by a linear shape laser of the present invention;

FIG. 2 is a diagram showing a laser irradiation apparatus in a preferredembodiment of the present invention;

FIG. 3 is an optical system which forms a linear shape laser beam of thepresent invention;

FIG. 4 is a diagram showing the state of a laser irradiation for adriver region of the present invention;

FIG. 5 is a diagram showing the relationship between the continuousemission laser output which can crystallize a non-single crystal siliconfilm formed on a glass substrate and the spot size of Embodiment 1;

FIG. 6 is a diagram showing the state of a laser irradiation for anentire substrate surface of Embodiment 5;

FIG. 7 is a diagram showing the state of a linear shape laser beamirradiation for an entire substrate surface of Embodiment 2;

FIG. 8 is a diagram showing an optical system for processing a laserbeam into a linear shape of Embodiment 2;

FIG. 9 is a diagram showing the state of a laser irradiation for themultiple substrate of Embodiment 6;

FIG. 10 is a diagram showing the state of a laser irradiation for themultiple substrate of Embodiment 7;

FIGS. 11A to 11D are diagrams showing the manufacturing process of anAM-LCD of Embodiment 8;

FIGS. 12A to 12D are diagrams showing the manufacturing process of anAM-LCD of Embodiment 8;

FIGS. 13A to 13C are diagrams showing the manufacturing process of anAM-LCD of Embodiment 8;

FIGS. 14A and 14B are diagrams showing an upper surface view and thecircuit arrangement of a pixel portion of Embodiment 8;

FIGS. 15A and 15B are diagrams showing the upper surface view of a CMOScircuit of Embodiment 8;

FIGS. 16A to 16C are diagrams showing the manufacturing process of anAM-LCD of Embodiment 9;

FIGS. 17A to 17D are diagrams showing the manufacturing process of anAM-LCD of Embodiment 9;

FIGS. 18A to 18C are diagrams showing the manufacturing process of anAM-LCD of Embodiment 9;

FIG. 19 is a circuit diagram of an active matrix type EL display deviceof Embodiment 12;

FIG. 20 is a diagram showing an external view of an AM-LCD of Embodiment12;

FIGS. 21A to 21F are diagrams showing examples of electronic equipmentof Embodiment 13;

FIGS. 22A to 22C are diagrams showing a surface of a silicon film lasercrystallized by a conventional linear shape laser;

FIGS. 23A and 23B are external views of an active matrix type EL displaydevice of Embodiment 12;

FIGS. 24A to 24D are diagrams showing examples of electronic equipmentof Embodiment 13; and

FIGS. 25A to 25C are diagrams showing examples of electronic equipmentof Embodiment 13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment Mode

A specific method of crystallizing an amorphous silicon film using acontinuous emission excimer laser is described here.

First, a 125×125×0.7 mm glass substrate (Corning 1737) is prepared as asubstrate. This substrate has sufficient durability up to a temperatureof 600° C. A 200 nm silicon oxide film is deposited on the glasssubstrate as a base film. In addition, a 55 nm thick amorphous siliconfilm is deposited on top. Plasma CVD is used for both film depositions.In addition, film deposition may be performed by a known depositionmethod such as sputtering.

The substrate, on which the above films have been deposited, is thenexposed to a hot bath at 450° C. for 1 hour. This process is one forreducing the concentration of hydrogen in the amorphous silicon film. Ifthere is too much hydrogen in the film, the film cannot completelywithstand the laser energy, so this step is added. A hydrogen density onthe order of 10²⁰ atoms/cm³ in the film is suitable.

A 1000 W KrF excimer laser is used as a continuous emission excimerlaser in this embodiment. The emission wavelength is 248 nm.

If the energy fluctuations of the excimer laser are held to within ±10%,preferably within ±3%, and more preferably within ±1%, during the laserprocessing of one substrate, then homogeneous crystallization can beperformed.

Laser energy fluctuation as stated throughout this specification isdefined below. Namely, the average value of laser energy during theperiod of irradiation of one substrate is taken as a standard, and forthe laser energy fluctuation, the difference between the average valueand the lowest energy or the highest energy during the period isexpressed by percentage.

In order to crystallize a silicon film without heating a glass substrateat an output of 1000 W, it is necessary to reduce the spot size of thelaser beam on the irradiation surface, and to increase the energydensity.

As written through this specification, “spot size” indicates the laserbeam size on all irradiation surfaces. The spot size at this time isdefined as the surface area of the region with an energy density greaterthan half of the largest laser energy density value.

The inventors of the present invention has calculated a heat balance atthe laser irradiation, and the largest spot size which can crystallizethe amorphous silicon film without imparting any thermal damage to theglass is estimated to be 0.5 mm². The thermal conductivity of the basesilicon oxide film was taken as 0.02 W/cm·K for this calculation. Inaddition, the thermal conductivity of the amorphous silicon film wastaken as 0.2 W/cm·K. These thermal conductivities depend upontemperature, but can be considered to be nearly constant from 300 K tothe melting point of the amorphous silicon film (this can be consideredon the order of 1200 to 1600 K). The details of this calculation areshown in embodiment 1.

The spot size calculated above is very small when compared to that of aconventional pulse emission excimer laser. Therefore, using a continuousemission excimer laser to form a linear shape laser beam with the samesize as the conventional, it is necessary to wait for the development ofa laser with an additionally higher output.

In order to utilize a continuous emission excimer laser, possessing thelargest spot size calculated above, in the manufacture of a liquidcrystal display device, for example, it may be used in thecrystallization of only the driver section of the low temperature TFTliquid crystal display device of an integrated driver and pixel. Ingeneral, there is a demand for good characteristics of a driver TFT of aliquid crystal display device, when compared to a pixel TFT. By usinglaser irradiation in only the driver section, the characteristics of thedriver can be made to improve by leaps and bounds. On the other hand,the pixel portion is satisfactory with the amorphous silicon as is.

The above laser is transformed into a 5 mm (corresponding to the widthof the driver)×0.1 mm size by use of a suitable optical system. Acombination of a cylindrical lens array and a condensing cylindricaltense is used in the optical system. Synthetically fused quartz, whichis transparent to ultraviolet light, is used as the lens materialconstituting the optical system. An AR coating process is performed sothat a 248 nm wavelength transmission ratio of over 99% can be obtainedin the tense surface. This is in order to increase the transmissionratio and the laser resistance.

The structure of the optical system may be, for example, that shown inFIG. 3. It has been calculated that the beam size of a 1000 W continuousemission excimer laser which may have stable emission is a circular beamwith a diameter on the order of 0.3 mm. Therefore, the beam is firstexpanded in one direction by using a beam expander structured bycylindrical lenses 301 and 302. The beam is next split by a cylindricallens array 303, and is additionally formed into a 5 mm long beam on theirradiation surface by a condensing cylindrical lens array 304.

A cylindrical lens 305 is placed at a right angle to the abovecylindrical lens, and the roughly 0.3 mm width beam is made into a 0.1mm width beam on the irradiation surface.

Note that the focal length and thickness of each of the lenses is aslisted below. The cylindrical lens 301 has a focal length of 10 mm and athickness of 2 mm; the cylindrical lens 302 has a focal length of 170 mmand a thickness of 5 mm; the cylindrical lens array 303 each has focallengths of 20 mm and thicknesses of 3 mm; the cylindrical lens 304 has afocal length of 100 nm and a thickness of 3 mm; and the cylindrical lens305 has a focal length of 20 mm and a thickness of 3 mm.

A mirror 203 is placed directly after the beam expander. This mirror isnot necessarily needed. The mirror is coated so that the reflectance ismaximized at an angle of incidence of 45 degrees.

The gap between the cylindrical lenses 301 and 302, which structure thebeam expander, is approximately 180 mm. The gap may be regulated ifnecessary so that the beam enters the full width of the cylindrical lensarray 303. The gap between the cylindrical lens array 303 and thecylindrical lens 304 is set at 120 mm.

The surface of the object to be irradiated is set 100 mm behind thecylindrical lens 304. In addition, the cylindrical lens 305 is placed ina position 14 mm from the surface of the object to be irradiated. Theabove values can be changed in order to perform fine tuning, ifnecessary, after actually setting the laser. The optical systemplacements may be in accordance with those given by geometrical optics.

If the above beam shape on the irradiation surface is a linear shapecontinuous emission excimer laser, and the energy distribution in thelongitudinal direction is within ±5%, then homogeneous crystallizationof the silicon film can be performed. With the energy distributionpreferably within ±3%, more preferably within ±1%, more homogeneouscrystallization can be performed.

An external view of a laser irradiation apparatus is shown in FIG. 2. Ancontinuous emission excimer laser beam is output from a laser emissiondevice 201, is processed into a linear shape by an optical system 202,and is irradiated to a substrate to be processed 204.

The laser irradiation is performed on an XY stage 205. The abovesubstrate is set on the XY stage, and the laser irradiation apparatus isset so that the laser is irradiated at one point of the XY stage 205.The laser focus is regulated to match the substrate surface. The XYstage 205 used has a positioning accuracy of 10 μm.

For example, the gap between a pixel and a driver of an integrateddriver and pixel type 3.5 inch liquid crystal display device is on theorder of 300 μm. Therefore in order to only irradiate the driver withoutirradiating the pixel, the accuracy of the above XY stage is sufficient.

The laser irradiation is, for example, performed while scanning the XYstage as shown in FIG. 4. The laser is made not to hit a pixel region208 at this time. The scanning speed may be suitably determined by theoperator, but a rough standard is to choose the speed in the range offrom 0.1 to 10 m/s. It is necessary to pre-run the XY stage beforeirradiation until the scanning speed reaches the predetermined speed.This process is performed for a source driver region 206 and a gatedriver region 207.

Thus the laser annealing process is completed. By repeating the aboveprocess, multiple substrates can be processed.

Embodiment 1

The calculation method of the relationship between the laser power andthe maximum spot size, estimated in the above embodiment mode of thepresent invention, is shown here.

The amorphous silicon film formed on the above substrate is taken as amodel. The thermal conductivities of the silicon oxide film and theamorphous silicon film are taken as 0.02 W/cm·K and 0.2 W/cm·K,respectively, from room temperature to 1200° C. (the temperature assumedto be the melting point of the amorphous silicon film used throughoutthis specification). The thermal conductivity in the range beyond themelting point temperature of the amorphous silicon film is taken as 2W/cm·K.

The temperature limitations of each of the films during lasercrystallization of the amorphous silicon film are as below.

The glass substrate can be heated up to a maximum of 600° C. without anychange in shape (the distortion temperature of Corning 1737 is above600° C.). On the other hand, if it is assumed that the temperature ofthe amorphous silicon film must exceed the film melting point entirely,then it must reach 1200° C.

It is taken that at a given instant during laser crystallization, thetemperature of the amorphous silicon film is 1200° C., and the interfacetemperature between the glass substrate and the silicon oxide film is600° C. (The thermal conductivity of the amorphous silicon film is 1 to2 orders of magnitude larger than that of the silicon oxide film, so itis assumed that the temperature of the amorphous silicon film becomesequal immediately.) In order to maintain this temperature distribution,it is necessary to supply to the amorphous silicon film an amount ofheat that exceeds the amount of heat escaped from the amorphous siliconfilm due to heat conductivity caused by the temperature gradient thatdevelops in the silicon oxide film.

The heat flow F (W/cm²) flowing in the silicon oxide film when thistemperature distribution is imparted is:

F = 0.02[W/cm ⋅ K] × (1200 − 600)[K]/2000 × 10⁻⁸[cm]   = 6 × 10⁵[W/cm²].

On the other hand, the output of the excimer laser used in thisspecification is 1000 W, so assuming that the laser spot size which cancrystallize the amorphous silicon film is S [cm²], and that the amountof heat supplied by the laser exceeds the amount of heat which isescaped from the silicon oxide film, then:S<1000[W]/F[W/cm²]<0.002[cm²].

This is less than half of the maximum spot size shown by the embodimentmode of the present invention. In addition, the merits of using acontinuous emission excimer laser with this size are few. Further, theabove result ignores the reflection of light from the surface of theamorphous silicon film.

The thickness of the Corning 1737 substrate used is 0.7 mm, so that thecalculation was redone with only the extreme surface of the substratepermitted to exceed the distortion point temperature. If the extremesurface of the substrate, only to a depth of 0.001 mm (1/700 of thesubstrate thickness), is assumed to exceed the distortion pointtemperature of the substrate, then the interface temperature between theglass substrate and the silicon oxide film can be increased to 1100° C.

The heat flow F′ (W/cm²) flowing in the silicon oxide film when thistemperature distribution is imparted is:

F^(′) = 0.02[W/cm ⋅ K] × (1200 − 1100)[K]/2000 × 10⁻⁸[cm]   = 1 × 10⁵[W/cm²].

On the other hand, the output of the excimer laser used in thisspecification is 1000 W, so assuming that the laser spot size which cancrystallize the amorphous silicon film is S′ [cm²], then:S′<1000[W]/F′[W/cm²]<0.01[cm²].

Approximately one-half of the energy is reflected from the amorphoussilicon film in the excimer laser wavelength region, resulting in:(Required laser spot size)<0.01[cm²]/2<0.005[cm²].This is the value used in the embodiment mode of the present invention.

Converting the above results for the continuous emission laser power Lw(W), necessary to crystallize the amorphous silicon film, and for thespot size Sp (cm²) into a relational equation, then:Lw/2Sp>F′,therefore,Lw>2×10⁵ Sp.

All calculations up to now have been performed while assuming that thebase film is a 200 nm thick silicon oxide film, that the semiconductorfilm is a 50 nm thick amorphous silicon film, and that the substrate isa 0.7 mm thick Corning 1737 substrate. Therefore, the above statedresults will change if other materials are used or if the thicknessesare changed, however the order of the results will not change.

For example, making the thickness of the base silicon oxide film 400 nmwith the above stated conditions, the results become:Lw>1×10⁵ Sp.  (Eq. A)

The minimum spot size required to crystalize the semiconductor film isnow considered. When crystallizing the semiconductor film with a spotsize smaller than a certain size, the amount of heat that flows awayfrom the outside of the spot (around the circumference of where the spothits the semiconductor film) due to heat conduction, becomes relativelylarge compared to the total amount of heat, so the crystallizationhomogeneity is harmed.

If the above minimum spot size is estimated a little on the large side,and if it is sufficient that the size of one side of the angular beam beon the order of 1000 times the film thickness, then:Sp>(50[nm]×1000)²Sp>2.5×10⁻⁵[cm²]  (Eq. B)A graph of the relationship between Eq. A and Eq. B is shown in FIG. 5.

Embodiment 2

The spot size calculated in embodiment 1 above is very small, so it isdifficult to use for mass production. An example of increasing the laserbeam size by a great jump through use of a high distortion pointtemperature quartz substrate as a substrate is shown, then, inembodiment 2. A quartz substrate does not change in shape, or inquality, at all when heated to the melting point of a silicon film.Therefore, the beam size can be made wider. The irradiation object inembodiment 2 is the substrate having a silicon film formed thereovershown in the embodiment mode of the present invention, where the glasssubstrate is replaced with a 1.1 mm thick quartz substrate.

An example using a 1000 W continuous emission excimer laser processedinto a linear beam shape (with a size of 125 mm×0.4 mm) is shown inembodiment 2. The means of processing the laser into a linear beam shapeis shown in FIG. 8.

The device shown in FIG. 8 possesses a function of irradiating as alinear shape beam 405 laser light (in this state it has a roughlyrectangular shape) from a laser emission device 406, through an opticalsystem shown by reference numerals 407, 408, 409, 410, and 412. A stage413 is a one axis stage which moves in one direction. A substrate placedon the stage 413 is irradiated by scanning.

Note that the size of the laser beam emitted from the laser emissiondevice is originally a 0.3 mm circular beam in diameter, but this isexpanded into a roughly 10×35 mm ellipse by using a two sets of beamexpanders (not shown). Reference numeral 411 denotes a mirror.

The above optical system is entirely manufactured from quartz. Quartz isused because it has a sufficiently high transmissivity for thewavelength range of an excimer laser. In addition, coating of theoptical system surface is performed with a coating appropriate for thewavelength of the excimer laser used (248 nm in this specification).Thus a transmissivity of at least 99% can be obtained by a single lense.Further, the durability of the lense is increased.

Reference numeral 407 denotes a cylindrical lens array, possessing afunction of splitting a beam into multiple beams. This multiple numberof split beams is synthesized into a single beam by a cylindrical lens410.

This structure is necessary in order to make the intensity distributionuniform within the beam. In addition, the combination of the cylindricallens array 408 and the cylindrical lens 409 possesses the same functionas the combination of the cylindrical lens array 407 and the cylindricallens 410.

The combination of the cylindrical lens array 407 with the cylindricallens 410 possesses a function of making the intensity distributionuniform in the longitudinal direction of the linear shape laser beam.The combination of the cylindrical lens array 408 with the cylindricallens 409 possesses a function of making the intensity distributionuniform in the width direction of the linear shape laser beam.

A beam with a beam width w is first formed by the combination of thecylindrical lens array 408 with the cylindrical lens 409. By passingthrough the mirror 411, and in addition by placing a doublet cylindricallens 412, a more fine linear shape laser beam (finer than the beam widthw) can be obtained.

The energy distribution of the linear shape laser beam formed by theoptical system of FIG. 8 shows a rectangular shape distribution whenlooking at a cross section in the width direction. In other words, alinear shape laser beam with extremely high homogeneity with regard toenergy density can be obtained.

Seven cylindrical lenses with a focal length of 41 mm, a width of 5 mm,a length of 30 mm, and a center thickness of 5 mm are used as thecylindrical lense array 407.

In addition, five cylindrical lenses with a focal length of 250 mm, awidth of 2 mm, a length of 60 mm, and a center thickness of 5 mm areused as the cylindrical lense array 408.

In addition, a cylindrical lense with a focal length of 200 mm, a widthof 30 mm, a length of 120 mm, and a center thickness of 10 mm is used asthe cylindrical lense 409.

In addition, a cylindrical lense with a focal length of 1022 mm, a widthof 180 mm, a length of 40 mm, and a center thickness of 35 mm is used asthe cylindrical lense 410.

In addition, cylindrical lenses with a width of 90 mm, a length of 160mm, and a center thickness of 16 mm are combined into a set with asynthetic focal length of 220 mm and used as the doublet cylindricallens 412.

Note that all of the above lenses have curvature in the width direction,and all are spherical lenses. The lens material is synthetic quartz, andan AR coating process is performed so that a transmissivity of at least99% can be obtained at a transmitted light wavelength of 248 nm.

In addition, the cylindrical lens array 407 is placed toward the laser,2100 mm from the irradiation surface, along the laser light path.

In addition, the cylindrical lens array 408 is placed toward the laser,1980 mm from the irradiation surface, along the laser light path.

In addition, the cylindrical lens 409 is placed toward the laser, 1580mm from the irradiation surface, along the laser light path.

In addition, the cylindrical lens 410 is placed toward the laser, 1020mm from the irradiation surface, along the laser light path.

In addition, the doublet cylindrical lense 412 is placed toward thelaser, 275 mm from the irradiation surface, along the laser light path.

The values stated above are rough standards, and depend upon themanufacturing precision of the lenses.

By scanning the linear shape continuous emission excimer laser beamprocessed into the above stated size using the method shown in FIG. 7,the entire silicon film surface is crystallized. Since the length of thelong side of the linear shape laser beam is greater than the length ofthe short side of the silicon film, the entire substrate surface can becrystallized by one scan. In FIG. 7 reference numeral 401 denotes asubstrate, 402 denotes a source driver region, 403 denotes a gate driverregion, 404 denotes a pixel region and 405 denotes a linear shape beamlaser light. As can be understood by looking at FIG. 7, the entiresilicon film is crystallized by one scan of the linear shape laser beam.

The scanning speed may be suitably chosen by the operator, but as arough guideline it is suitably selected in the range of from 0.5 to 100mm/s. At this time it is necessary to pre-run the XY stage beforeirradiation until the scanning speed reaches the predetermined speed.

Embodiment 3

Embodiment 3 shows a process of crystallizing a silicon film formed on aglass substrate using a 1000 W continuous emission excimer laser withthe same specifications as that of embodiment 2. An example is shown inwhich the extreme surface of the glass substrate melts by thecrystallization process of embodiment 3, so a base film is made ratherthick in order to prevent contamination of the silicon film.

First, a 125×125×0.7 mm glass substrate (Corning 1737) is prepared as asubstrate. This substrate has sufficient durability up to a temperatureof 600° C. A 400 nm silicon oxide film is deposited on the glasssubstrate as a base film. In addition a 55 nm thick amorphous siliconfilm is deposited on top. Sputtering is used for both film depositions.Alternately, film deposition may also be performed by plasma CVD.

The substrate, on which the above films have been deposited, is thenexposed to a hot bath at 450° C. for 1 hour. This process is one forreducing the concentration of hydrogen in the amorphous silicon film. Ifthere is too much hydrogen in the film, the film cannot completelywithstand the laser energy, so this step is added. A hydrogen density onthe order of 10²⁰ atoms/cm³ in the film is suitable.

The thickness of the Corning 1737 substrate used is 0.7 mm, so acalculation was performed with only the surface of the substratepermitted to exceed the distortion point temperature. If the surface ofthe substrate, to a depth of only 0.1 mm ( 1/7 of the substratethickness), is assumed to exceed the distortion point temperature, thenthe interface temperature between the glass substrate and the siliconoxide film can be increased to 1198° C.

The heat flow F″ (W/cm²) flowing in the silicon oxide film when thistemperature distribution is imparted is:

F^(″) = 0.02[W/cm ⋅ K] × (1200 − 1198)[K]/4000 × 10⁻⁸[cm]   = 1 × 10³[W/cm²].

On the other hand, the output of the excimer laser used in thisspecification is 1000 W, so assuming that the laser spot size which cancrystallize the amorphous silicon film is S″ [cm²], then:S″<1000[W]/F″[W/cm²]<1[cm²].

Approximately one-half of the energy is reflected from the amorphoussilicon film in the excimer laser wavelength region, resulting in:(Required laser spot size)<1[cm²]/2<0.5[cm²].

The spot size of the laser beam used in embodiment 3 is:0.4×125mm=0.5[cm²],corresponding to the maximum value of the above results.

Converting the above results for the continuous emission laser power Lw(W), necessary to crystallize the amorphous silicon film, and for thespot size Sp (cm²) into a relational equation, then:Lw/2Sp>F″,therefore,Lw>2×10³ Sp.

All calculations up to now have been performed while assuming that thebase film is a 400 nm thick silicon oxide film, that the semiconductorfilm is a 55 nm thick amorphous silicon film, and that the substrate isa 0.7 mm thick Corning 1737 substrate. Therefore, the above statedresults will change if other materials are used or if the thicknessesare changed; however the order of the results will not change.

Embodiment 4

A method of irradiating a polycrystal silicon film with a continuousemission excimer laser is shown in embodiment 4.

Corning 1737 is used as a glass substrate. A 200 nm thick silicon oxidefilm and a 50 nm thick amorphous silicon film are deposited in order onone face of the substrate. Afterward, this is exposed to a nitrogenatmosphere at 600° C. for 24 hours, crystallizing the amorphous siliconfilm.

In addition, the technique described in embodiment 2 of Japanese PatentApplication Laid-open No. Hei 7-130652 (corresponding to U.S. Pat. No.08/329,644) may be used for crystallization of the amorphous siliconfilm. The technique described in the above publication is a techniquefor performing crystallization by which a catalytic element forpromoting crystallization (cobalt, palladium, germanium, platinum, iron,copper, typically nickel) is selectively maintained in the surface ofthe amorphous silicon film, with that section used as a seed for growth.

First, an aqueous nickel acetate solution with a concentration of 10 ppmmay be applied on the amorphous silicon film, and this may be exposed toa nitrogen atmosphere at 550° C. for 4 hours, performing crystallizationof the amorphous silicon film. Spin coating may be used as theapplication method.

The amorphous silicon film added with nickel by this technique iscrystallized at a low temperature over a short time. It is thought thatthe cause of this is that the nickel fulfills the role of a crystalgrowth nucleus, promoting the crystal growth.

There are many defects included in the amorphous silicon filmcrystallized by the above method due to the low crystallizationtemperature, and there are cases in which it is insufficient for use asa semiconductor element material. Thus, in order to increase thecrystallization of the polycrystalline silicon film, the film isirradiated with a laser.

The laser used is the one employed in the embodiment mode of the presentinvention. Further, the laser irradiation method may also be the same asthat of the embodiment mode of the present invention. The relationshipshown in embodiment 1 between the laser output and the spot sizerequired to crystallize the amorphous silicon film is the same for apolycrystalline silicon film.

The reason is that number of defects exist within the polycrystalsilicon film. The defect regions possess the same physical properties asthose of amorphous silicon, so the laser irradiation method shown in theembodiment mode of the present invention can be used to restore theregions with defects.

Embodiment 5

A crystallization method of the entire surface of a substrate by laseris shown in embodiment 5. In the embodiment mode of the presentinvention, crystallization of only the driver region was performed, butthe entire substrate surface is irradiated with laser in embodiment 5.

The laser used is the one shown in FIG. 2. The beam length is 5 mm, sothe entire substrate surface is laser irradiated while shifting thescanning position by 5 mm at a time. Controlling the overlappingsections between one laser scanning region and the neighboring scanningregion is very important.

The characteristics are rather poor in the sections in which the laseroverlaps, as explained before. Therefore, the overlapping regions areset so as not to go into element regions. The overlapping sections areexposed to attenuated energy regions at the tips of the laser beam inthe longitudinal direction. Although it depends upon the precision ofthe optical system forming the laser beam, with the presenttechnological standards, the attenuated regions can be suppressed on theorder of 50 μm.

Therefore, the 5 mm long laser beam used in embodiment 5 is irradiatedover the entire substrate surface with an overlap of 50 μm. The locationof element channel forming regions, offset regions, and LDD regions areset so as not to be in the overlapped regions.

The entire surface irradiation state is shown in FIG. 6.

Embodiment 6

When liquid crystal panels are mass produced, generally a method isperformed in which one substrate is sectioned after completing theformation processing of a plural number of panels on the substrate.

In embodiment 6, an example of irradiating this kind of multiplesubstrate with a linear shape laser beam having a continuous lightemission excimer laser emission device as a light source is shown. Thesize of the multiple substrate is 600 mm×720 mm throughout embodiment 6.

Many methods of irradiating a linear shape laser on a multiple substratecan be considered, and a typical one is given and explained inembodiment 6.

The method used in embodiment 6 is shown in FIG. 9. The laser lightemitted from a continuous light emission excimer laser emission device1301 is made into a linear shape laser beam 1304 on an irradiationsurface (a substrate 1306) by passing through an optical system 1302 anda mirror 1303. One of the examples shown in the previous embodiment, forexample, that shown in FIG. 8, is used in the optical system 1302.

A 5×6 array of 3.5 inch liquid crystal panels, for a total of 30 panels,are formed on the substrate 1306 in embodiment 6. The size of themultiple substrate is 600 mm×720 mm, so one panel is enclosed in asquare region 120 mm×120 mm. For simplicity, only four liquid crystalpanels are shown in FIG. 9. A region 1307 which becomes a source driver,a region 1308 which becomes a gate driver, and a region 1309 whichbecomes a pixel are shown for one liquid crystal panel.

The length of the linear shape laser beam formed by the optical systemshown in FIG. 8 is 125 mm, so this is longer than the length of a sideof a region enclosing one panel (a 120 mm square). Therefore, a onecolumn region of panels can be processed by scanning the linear shapelaser beam only one time in one direction. The panels are arranged infive columns by six rows on the multiple substrate 1306, so the entiresubstrate surface can be laser irradiated by scanning five times.Scanning of the substrate is performed by moving an XY stage 1305. Thesubstrate scanning direction, for example, is in the direction shown bythe dotted linear arrow in FIG. 9.

Note that while only four liquid crystal panels are shown in FIG. 9,there is of course no special limit.

Embodiment 7

Another example of irradiating a multiple substrate with a linear shapelaser beam having a continuous light emission excimer laser emissiondevice as a light source is shown in embodiment 7. The size of themultiple substrate is 600 mm×720 mm throughout embodiment 7.

The method used in embodiment 7 is shown in FIG. 10. The laser lightemitted from a continuous light emission excimer laser emission device1401 is made into a linear shape laser beam 1404 on an irradiationsurface (a substrate 1406) by passing through an optical system 1402 anda mirror 1403. One of the examples shown in the previous embodiment, forexample, that shown in FIG. 8, is used in the optical system 1402.

A 10×12 array of 2.6 inch liquid crystal panels, for a total of 120panels, are formed on the substrate 1406 in embodiment 7. The size ofthe multiple substrate is 600 mm×720 mm, so one panel is enclosed in asquare region 60 mm×60 mm. For simplicity, only four liquid crystalpanels are shown in FIG. 10. A region 1407 which becomes a sourcedriver, a region 1408 which becomes a gate driver, and a region 1409which becomes a pixel are shown for one liquid crystal panel.

The length of the linear shape laser beam formed by the optical systemshown in FIG. 8 is 125 mm, so this is longer than the length of theabove four panels arranged in 2 columns by 2 rows (a 120 mm square).Therefore, two column regions of panels can be processed by scanning thelinear shape laser beam only one time in one direction. The panels arearranged in 10 columns by 12 rows on the multiple substrate 1406, so theentire substrate surface can be laser irradiated by scanning five times.Scanning of the substrate is performed by moving an XY stage 1405. Thesubstrate scanning direction, for example, is in the direction shown bythe dotted line arrow in FIG. 10.

The longer the length of the linear shape laser beam becomes, or thesmaller the panels become, the more the number of panels that can belaser irradiated by one scan of the linear shape laser beam increases.Depending upon the length of the linear shape laser beam and the panelsize, three columns or more can be laser irradiated by a single scan ofthe linear shape laser beam.

Note that while only four liquid crystal panels are shown in FIG. 10,there is of course no special limit.

Embodiment 8

An example of the manufacture of a TFT (thin film transistor) using thecrystalline silicon film obtained in embodiment mode 1 of the presentinvention, or any of the above embodiments, is shown in embodiment 8.The processes of embodiment 8 are shown in FIG. 11A to 13C.

A glass substrate 701 is first prepared as a substrate, and a 200 nmthick silicon oxide film (also called a base film) 702 and a 55 nm thickamorphous silicon film 703 a are deposited on top in succession, withoutexposure to the atmosphere. (See FIG. 11A.) Doing so can prevent theadsorption of impurities such as boron, which present in the atmosphere,on the lower surface of the amorphous silicon film 703 a.

Note that an amorphous silicon film is used as an amorphoussemiconductor film in embodiment 8, but other semiconductor films mayalso be used. An amorphous silicon germanium film is also fine. Inaddition, PCVD, LPCVD, or sputtering may be used as the formation meansfor the base film and the semiconductor film. For cases in which thehydrogen concentration is high, heat treatment may be performed next inorder to reduce the hydrogen concentration.

Crystallization of the amorphous silicon film 703 a is performed next.Laser crystallization using the laser irradiation technique shown in theembodiment mode of the present invention is performed in embodiment 8.Thus laser irradiation is performed, causing crystallization, andforming a region 704 a from a crystalline silicon (polysilicon) film.(See FIG. 11B.)

The crystalline silicon (polysilicon) film formed is then patterned,forming a semiconductor layer 704 b of a TFT. (See FIG. 11C.)

Note that the doping of an impurity element (phosphorous or boron) intothe crystalline silicon film may be performed before or after theformation of the semiconductor layer 704 b in order to control the TFTthreshold voltage. This process may be performed on only an NTFT or aPTFT, or may be performed on both.

An insulating film 705 is formed next by sputtering or plasma CVD, and afirst conductive film 706 a and a second conductive film 707 a arelaminate formed by sputtering. (See FIG. 11D.)

The insulating film 705 is an insulating film functioning as a TFT gateinsulating film, and its film thickness is set between 50 and 200 nm. A100 nm thick silicon oxide film is formed in embodiment 8 by sputteringusing a silicon oxide as a target. In addition, not only a silicon oxidefilm, but a laminate structure of a silicon nitride film formed on asilicon oxide film can be used, and a silicon nitride oxide film inwhich nitrogen is doped into a silicon oxide film may be used.

Note that an example is shown in embodiment 8 in which patterning isperformed and a gate insulating film is formed after performing lasercrystallization of the amorphous silicon film, there are no speciallimitations on process order, and a process may be used in which lasercrystallization and then patterning are performed after depositing anamorphous silicon film and a gate insulating film in succession bysputtering. Good interface characteristics can be obtained withsuccessive deposition by sputtering.

In addition, the first conductive film 706 a is made from a conductivematerial containing as a main component an element selected from Ta, Ti,Mo, and W. The first conductive film 706 a may be formed with athickness of 5 to 50 nm, preferably between 10 and 25 nm. On the otherhand, a conductive material with Al, Cu, or Si as its main component isused for the second conductive film 707 a. The second conductive film707 a may be formed with a thickness of 100 to 1000 nm, preferablybetween 200 and 400 nm. The second conductive film 707 a is formed inorder to reduce the resistance of a gate wiring or a gate bus linewiring.

Unnecessary areas of the second conductive film 707 a are removed nextby patterning, forming an electrode 707 b which becomes a portion of thegate bus line in the wiring section. Resist masks 708 a to 708 d areformed afterward. The resist mask 708 a is formed to cover the PTFT, andthe resist mask 708 b is formed to cover a channel forming region of adriver circuit NTFT. In addition, the resist mask 708 c is formed tocover the electrode 707 b, and the resist mask 708 d is formed to covera channel forming region of a pixel portion. Doping of an impurityelement which imparts n-type conductivity is performed with the resistmasks 708 a to 708 d as masks, forming impurity regions 710 and 711.(See FIG. 12A.)

Phosphorous is used as an n-type conductivity imparting impurity elementin embodiment 8, and ion doping using phosphine (PH₃) is performed. Theacceleration voltage is set high at 80 keV for this process in order todope phosphorous through the gate insulating film 705 and through thefirst conductive film 706 a, and into the semiconductor layer 704 bbelow. The concentration of phosphorous doped into the semiconductorlayer 704 b is preferably in the range of from 1×10⁶ to 1×10¹⁹atoms/cm³, and is set to 1×10¹⁸ atoms/cm³ here. Thus the regions 710 and711 in which phosphorous is doped are formed in the semiconductor layer.A portion of the phosphorous doped region formed here functions as anLDD region. In addition, a portion of the regions covered with masksinto which phosphorous is not doped (regions 709 and 712 from thecrystalline silicon film) functions as a channel forming region.

Note that an ion implantation, in which separation of mass is performed,may be used for the phosphorous doping process, and that plasma doping,in which separation of mass is not performed, may be used. Furthermore,conditions such as acceleration voltage and dose amount may be optimallyset by the user.

Next, the resist masks 708 a to 708 d are removed, and an activationprocess is performed if necessary. Then a third conductive film 713 a isdeposited by sputtering. (See FIG. 12B.) The third conductive film 713 ais a conductive material containing as a main component selected fromTa, Ti, Mo, and W. Further, the thickness of the third conductive film713 a is between 100 and 1000 nm, preferably from 200 to 500 nm.

Resist masks 714 a to 714 d are newly formed next, and patterning isperformed, forming gate electrodes 706 b and 713 b of the PTFT, andwirings 706 c and 713 c. An impurity element which imparts p-typeconductivity is doped next using the masks 714 a to 714 d as is, forminga source region and a drain region of the PTFT. (See FIG. 12C) Boron isused here as the impurity element, and is doped by ion doping usingdiborane (B₂H₆). The acceleration voltage is also set to 80 keV, andboron is doped to a concentration of 2×10²⁰ atoms/cm³ here.

The resist masks 714 a to 714 d are removed next, and resist masks 718 ato 718 e are newly formed. Afterward, etching is performed using theresist masks 718 a to 718 e as masks, forming gate wirings 706 d and 713d of the NTFT, gate wirings 706 e and 713 e of the pixel portion TFT,and upper wirings 706 f and 713 f of a storage capacitor. (See FIG.12D.)

After removing the resist masks 718 a to 718 e and forming new resistmasks 719, an impurity element which imparts n-type conductivity isdoped into the source region and drain region of the NTFT, formingimpurity regions 720 to 725. (See FIG. 13A.) Ion doping using phosphine(PH₃) is performed here. The concentration of phosphorous doped into theimpurity regions 720 to 725 is higher compared to the concentration inthe previous doping process in which an n-type conductivity impartingimpurity element is doped, is preferably between 1×10¹⁹ and 1×10²¹atoms/cm³, and is set to 1×10²⁰ atoms/cm³ here.

After next removing the resist masks 719, the state of FIG. 13B can beobtained by forming a protection film 727 from a 50 nm thick siliconnitride film.

An activation process is next performed in order to activate the dopedimpurity elements which impart n-type or p-type conductivity. Thermalannealing using an electric furnace, laser annealing using the aboveexcimer laser, or rapid thermal annealing (RTA) using a halogen lamp maybe performed for this process. The temperature is set to between 300 and700° C., preferably from 350 to 550° C., for heat treatment processing.Heat treatment is performed in embodiment 8 in a nitrogen atmosphere at450° C. for two hours.

Next, a contact hole is formed after forming a first interlayerinsulating film 730. Then, source electrodes and drain electrodes731–735 are formed with a known technique.

A passivation film 736 is formed next. A silicon oxide film, a siliconnitride oxide film, an silicon oxide nitride film, or a laminate film ofthese insulating films and a silicon oxide film can be used as thepassivation film 736. A 300 nm thick silicon nitride film is used inembodiment 8 as the passivation film.

Note that plasma processing is performed in embodiment 8 using ammoniagas as a pre-process before forming the silicon nitride film, and thatthe passivation film 736 is then formed as is. The hydrogen which isactivated (excited) by the plasma in this pre-process is locked up bythe passivation film 736, so hydrogen termination of the TFT activelayer (semiconductor layer) can be promoted.

In addition, if a gas containing hydrogen and a nitrogen monooxide gasare added, the surface of the body to be processed is cleaned bymoisture generated and contamination especially due to boron, etc.,contained in the atmosphere can be effectively prevented.

After forming the passivation film 736, a 1 μm thick acrylic film isformed as a second interlayer insulating film 737, patterned, a contacthole is formed, and a pixel electrode 738 is formed from an ITO film.Thus an AM-LCD with the structure shown in FIG. 13C is completed.

The channel forming region 709, the impurity regions 720 and 721, and aLDD region 728, are formed in the driver circuit NTFT by the aboveprocesses. The impurity region 720 becomes a source region, and theimpurity region 721 becomes a drain region. In addition, the channelforming region 712, the impurity regions 722 to 725, and an LDD region729 are formed in the pixel portion NTFT. Each of the LDD regions 728and 729 has portions to overlap the gate electrode (GOLD region), andnot to overlap the gate electrode (LDD region).

On the other hand, a channel forming region 717, and impurity regions715 and 716 are formed in the p-channel type TFT. The impurity region715 then becomes a source region, and the impurity region 716 becomes adrain region.

If a TFT manufactured using semiconductor films formed in accordancewith the above method is used, for example, when manufacturing a liquidcrystal display device, then a device can be obtained in which the laserprocessing marks do not stand out compared to the conventional. This isdue to the suppression of dispersion in the characteristics ofindividual TFTs, especially of dispersion of the mobility.

An example of the circuit structure of an active matrix type liquidcrystal display device is shown in FIG. 14A. The active matrix typeliquid crystal display device of embodiment 8 possesses a source signalline side driver circuit 501, a gate signal line side driver circuit (A)507, a gate signal line side driver circuit (B) 511, a pre-chargecircuit 512, and a pixel portion 506.

The source signal line side driver circuit 501 is provided with a shiftregister circuit 502, a level shifter circuit 503, a buffer circuit 504,and a sampling circuit 505.

In addition, the gate signal line side driver circuit (A) 507 isprovided with a shift register circuit 508, a level shifter circuit 509,and a buffer circuit 510. The gate signal line side driver circuit (B)511 is also structured similarly.

Furthermore, an optimal shape for the TFTs which structure each of thecircuits can be built in with the present invention by the same process,because it is easy to differ the length of the LDD regions on the samesubstrate by considering the NTFT driver voltages.

In addition, FIG. 14B shows an upper surface diagram of the pixelportion, and the cross sectional structure of the TFT taken along thelines of A–A′ and that of the wirings taken along the line of B–B′correspond to FIG. 13C, so some of the same symbols are used. In FIG.14B, reference numeral 601 denotes a semiconductor layer, 602 denotes agate electrode, and 603 denotes a capacitor line. The gate electrodesand the gate wirings, formed from first conducting layers and thirdconducting layers, and the gate bus lines, formed from first conductivelayers, second conductive layers, and third conductive layers, possess aclad structure in embodiment 8.

In addition, FIG. 15A shows an upper surface diagram of a CMOS circuitthat becomes a portion structuring the driver circuit, and correspondsto FIG. 13C. Reference numeral 1139 denotes a source electrode and 1141denotes a drain electrode of a PTFT, 1142 denotes a source electrode ofan NTFT, and 1120 and 1121 denote gate wirings. Furthermore, althoughthe active layers of the NTFT and the PTFT are in direct contact inembodiment 8, and the drain electrodes are shared, there are noparticular limitations on this structure, and the structure shown inFIG. 15B (a structure in which the active layers are completelyseparated) may be used. Note that in FIG. 15B, reference numeral 1239denotes a PTFT source electrode, 1241 denotes a drain electrode, 1241denotes an NTFT source electrode, and 1220 and 1221 denote gate wirings.

In addition, the constitution of embodiment 8 can be freely combinedwith the composition of any of embodiments 1 to 7.

Embodiment 9

FIG. 16A to 18C are used in embodiment 9 to explain an example of themanufacture of an AM-LCD using processes different from those ofembodiment 8. An example of a top gate type TFT is shown in embodiment8, but an example of a bottom gate type structure is shown in embodiment9.

First, a laminate structure (for simplicity, this is not shown in thefigures) gate electrode 802 is formed on a glass substrate 801. Atantalum nitride film and a tantalum film are deposited by usingsputtering in embodiment 9, and gate wirings (including gate electrodes)802 a to 802 c and a capacitor wiring 802 d are formed using a knownpatterning technique.

A gate insulating film and an amorphous semiconductor film are nextdeposited in order without exposure to the atmosphere. A laminate of asilicon nitride film and a silicon oxide film is formed by sputtering inembodiment 9, and a gate insulating film with a laminate structure isformed. (See FIG. 16A.) An amorphous silicon film is formed next withoutexposure to the atmosphere. Heat treatment may be performed afterward inorder to reduce the hydrogen concentration.

Laser crystallization is performed next, forming a crystalline siliconfilm 806. In embodiment 9, the amorphous semiconductor film isirradiated with laser light using the laser irradiation method shown inthe embodiment mode of the present invention. (See FIG. 16B.)

A channel protection film 807 for protecting the channel forming regionis formed next. The channel protection film 807 may be formed using aknown patterning technique. Patterning is performed in embodiment 9using a photo mask. In this state, the surface of the crystallinesilicon film, except for the regions contacting the channel protectionfilm 807, are exposed. (See FIG. 16C.) Furthermore, the photo mask isnot necessary in cases where patterning is done using exposure from theback surface so the number of process steps can be reduced.

A resist mask 808, coving a portion of the PTFT and the NTFT, is formednext by patterning the photo mask. Doping of an impurity element whichimparts n-type conductivity (phosphorous is used in embodiment 9) isthen performed, forming an impurity region 809. (See FIG. 17A.)

After next removing the resist mask 808, the entire surface is coveredby an insulating film 810 with a thin film thickness. The thininsulating film 810 is formed in order to dope a low concentration of animpurity element, and is not especially necessary. (See FIG. 17B.)

An impurity element with a low concentration, compared to the previousimpurity element doping process, is doped next. (See FIG. 17C.) Thus thecrystalline silicon film covered by the channel protection film 807 bbecomes a channel forming region 813, and the crystalline silicon filmcovered by the channel protection film 807 c becomes a channel formingregion 814 in accordance with this process. In addition, LDD regions 811and 812 of the NTFT are formed by this process.

A resist mask 815 is formed next to cover the entire surface of then-channel type TFT, and an impurity element which imparts p-typeconductivity is doped. (See FIG. 17D.) Thus the crystalline silicon filmcovered by the channel protection film 807 a becomes a channel formingregion 816 of the PTFT in accordance with this process, and a source anddrain region 817 of the PTFT is formed by this process.

After next removing the resist mask 815, the semiconductor layers arepatterned into the desired shape. (See FIG. 18A.) Here, referencenumeral 818 indicates a source region of the PTFT of the driver circuit;819, a source region of the NTFT of the driver circuit; 820, a sourceregion of the NTFT of the pixel portion; and 821, a drain region of theNTFT of the pixel portion and a capacitor electrode.

Next, after forming a first interlayer insulating film 822, a contacthole is formed, and source electrodes and drain electrodes 823 to 827are formed by a known technique.

A passivation film 828 is formed afterward. A silicon nitride film, asilicon nitride oxide film, a silicon oxide nitride film, or a laminatefilm of these insulating films and a silicon oxide film can be used as apassivation film 828. A 300 nm thick silicon nitride film is used as thepassivation film in embodiment 9. (See FIG. 18B.)

Note that plasma processing is performed in embodiment 9 using ammoniagas as a pre-process before forming the silicon nitride film, and thatthe passivation film 828 is then formed as it is. The hydrogen which isactivated (excited) by the plasma in this pre-process is locked up bythe passivation film 828, so hydrogen termination of the TFT activationlayer (semiconductor layer) can be promoted.

After forming the passivation film 828, a 1 μm thick acrylic film isformed as a second interlayer insulating film 829, a contact hole isformed by patterning, and a pixel electrode 830 is formed from an ITOfilm. Thus an AM-LCD with the structure shown in FIG. 18C is completed.

If a TFT manufactured using semiconductor films formed in accordancewith the above method is used, for example, when manufacturing a liquidcrystal display device, then a device can be obtained in which the laserprocessing marks do not stand out compared to the conventional. This isdue to the suppression of dispersion in the characteristics ofindividual TFTs, especially of dispersion of the mobility.

In addition, the constitution of embodiment 9 can be freely combinedwith the constitution of any of embodiments 1 to 7.

Embodiment 10

A case is explained in embodiment 10 in which a different means is usedto form the crystalline silicon film of embodiment 8.

Nickel is selected as a catalytic element in embodiment 10, a layercontaining nickel is formed on an amorphous silicon film, and after heattreatment (atmosphere of at 550° C. for 4 hours), crystallization isperformed by conducting the laser irradiation processes shown in theembodiment mode of the present invention.

A resist mask is formed next on the silicon film, and a periodic tablegroup 15 element (phosphorous is used in embodiment 10) doping processis performed. It is preferable that the concentration of the dopedphosphorous be between 5×10¹⁸ and 1×10²⁰ atoms/cm³ (more preferably from1×10¹⁹ to 5×10¹⁹ atoms/cm³). However, the required concentration ofphosphorous changes in accordance with the temperature of a latergettering process, with its process time, and in addition, with thesurface area of the phosphorous doped region, so the concentration isnot limited to this range. Thus regions into which phosphorous has beendoped (hereinafter called phosphorous doped regions) are formed.

The resist mask is placed so as to expose a portion of (or all of) aregion which later becomes a source region or a drain region of a drivercircuit TFT. In addition, in the similar manner the resist mask isplaced so as to expose a portion of (or all of) a source region or adrain region of a pixel TFT. The resist mask is not placed in a regionwhich becomes a lower electrode of a storage capacitor at this point, sophosphorous is doped over this entire surface, forming a phosphorousdoped region.

The resist mask is removed next, gettering of the catalytic element(nickel in embodiment 10) used in crystallization of the silicon film isperformed by heat treatment at between 500 and 650° C. for 2 to 16hours. In order to produce a gettering action, a temperature of within±50° C. of the maximum temperature in the thermal history is required.Heat treatment for crystallization is performed at between 550 and 600°C., so heat treatment at 500 to 650° C. can be sufficient to produce agettering action.

The crystalline silicon (polysilicon) film with a reduced catalyticelement concentration is then patterned, forming a TFT crystallinesemiconductor layer. Further processing may be performed in accordancewith embodiment 8.

Note that it is possible to freely combine the constitution ofembodiment 10 with the constitution of any of embodiments 1 to 9.

Embodiment 11

It is possible to use the present invention when forming an interlayerinsulating film on a conventional MOSFET, and then forming a TFTthereon. In other words, it is possible to realize a semiconductordevice with a three dimensional structure in which a reflective typeAM-LCD is formed on a semiconductor circuit.

In addition, the semiconductor circuit may be formed on an SOI substrateby SIMOX, Smart-Cut (a registered trademark of SOITEC corporation),ELTRAN (a registered trademark of Cannon, Inc.), etc.

Note that a combination of the constitutions of any of embodiments 1 to10 may be used when carrying out embodiment 11.

Embodiment 12

The case of forming a TFT on a substrate by the manufacturing processesshown in embodiment 8, and actually manufacturing an AM-LCD is explainedin embodiment 12.

After obtaining the state of FIG. 13C, an 80 nm thick alignment film isformed on the pixel electrode 738. A color filter, a transparentelectrode (opposing electrode), and an alignment film are formed on aglass substrate prepared as an opposing substrate, and a rubbing processis performed for each alignment film. The substrate on which the TFT isformed and the opposing substrate are then joined together using asealing material (sealant). A liquid crystal material is then maintainedtherebetween. A known means may be used for the cell construction, so adetailed explanation is omitted.

The following can be given as examples of the above liquid crystalmaterial: a TN liquid crystal; PDLC; a ferroelectric liquid crystal; ananti ferroelectric liquid crystal: and a mixture of a ferroelectricliquid crystal and an antiferroelectric liquid crystal. In addition, itis possible to use the liquid crystal materials disclosed in: H. Furueet al., “Characteristics and Driving Scheme of Polymer-stabilizedMonostable FLCD Exhibiting Fast Response Time and High Contrast Ratiowith Gray-scale Capability,” SID. 1998; T. Yoshida et al., “A Full-colorThresholdless Antiferroelectric LCD Exhibiting Wide Viewing Angle withFast Response Time,” SID Digest, 841, 1997; and U.S. Pat. No. 5,594,569.

In particular, among thresholdless antiferroelectric liquid crystalmaterials and thresholdless antiferroelectric mixed liquid crystalmaterials which are liquid crystal materials mixed from a ferroelectricliquid crystal material and an antiferroelectric liquid crystalmaterial, materials that have a driver voltage on the order of ±2.5 Vstand out. When this kind of low driver voltage thresholdlessantiferroelectric mixed liquid crystal is used, it is possible to limitthe power supply voltage of the image signal sampling circuit on theorder of 5 to 8 V, so this is effective for cases using a TFT with arelatively small width LDD region (for example, between 0 and 500 nm, orbetween 0 and 200 nm).

Note that a low voltage driver is realized by using a thresholdlessantiferroelectric mixed liquid crystal, so a liquid crystal displaydevice which has been made low power consumption is realized.

Note also that spacers may optionally be attached in order to maintain acell gap. Therefore, spacers do not need to be attached for cases whenthe call cap can be maintained without spacers, as for an AM-LCD with a1 inch diagonal or less.

Next, an external view of an AM-LCD manufactured as above is shown inFIG. 20. An active matrix substrate and an opposing substrate areopposing, as shown in FIG. 20, and a liquid crystal is sandwichedbetween the substrates. The active matrix substrate has a pixel portion1001, a scanning line driver circuit 1002, and a signal line side drivercircuit 1003 formed on a substrate 1000.

The scanning line driver circuit 1002 and the signal line side drivercircuit 1003 are connected to the pixel portion 1001 by scanning lines1030 and signal lines 1040, respectively. The driver circuits 1002 and1003 are principally structured by CMOS circuits.

The scanning lines 1030 are formed for each row of the pixel portion1001 and signal lines 1040 are formed for each column. Pixel TFTs 1010are formed near the intersections of the scanning lines 1030 and thesignal lines 1040. The gate electrodes of the pixel TFTs 1010 areconnected to the scanning lines 1030, and the sources are connected tothe signal lines 1040. In addition, pixel electrodes 1060 and storagecapacitors 1070 are connected to the drains.

A transparent conductive film such as an ITO film is formed over theentire substrate surface of an opposing substrate 1080. The transparentconductive film is an opposing electrode for the pixel electrodes 1060of the pixel portion 1001, and the liquid crystal material is driven bythe electric field formed between the pixel electrodes and the opposingelectrode. An alignment film, a black mask, or a color filter may beformed on the opposing substrate 1080 if necessary.

IC chips 1032 and 1033 are installed to the substrate on the activematrix substrate side, on the face to which an FPC 1031 is installed.The IC chips 1032 and 1033 are structured with circuits such as videosignal processing circuits, timing pulse generation circuits, γcorrection circuits, memory circuits, and computation circuits formed ona silicon substrate.

In addition, an example of a liquid crystal display device is given andexplained in embodiment 12, but it is possible to apply the presentinvention to an EL (electroluminescence) display device, or to an EC(electrochromic) display device, provided that it is an active matrixtype display device.

An example of an application to an active matrix type EL display deviceis shown in FIG. 19.

FIG. 19 is a circuit diagram of an active matrix type EL display device.Reference numeral 11 denotes a pixel portion, and an x-directionperipheral driver circuit 12 and a y-direction peripheral driver circuit13 are formed in the surrounding area. In addition, each pixel of thepixel portion 11 has a switching TFT 14, a capacitor 15, a currentcontrol TFT 16, and an organic EL element 17, and an x-direction signalline 18 a (or 18 b), and a y-direction signal line 20 a (or 20 b, 20 c)are connected to the switching TFT 14. Further, power supply lines 19 aand 19 b are connected to the current control TFT 16.

The structure of the TFTs used in the x-direction peripheral drivercircuit 12 and the y-direction peripheral driver circuit 13 in theactive matrix type EL display device of embodiment 12 is a GOLDstructure, and the TFT structure of the switching TFT 14 and the currentcontrol TFT 16 is an LDD structure.

In addition, FIG. 23A is a top view of an EL display device using thepresent invention. In FIG. 23A reference numeral 4010 denotes asubstrate, 4011 denotes a pixel portion, 4012 denotes a source sidedriver circuit, and 4013 denotes a gate side driver circuit. The drivecircuits lead to an FPC 4017 through gate wirings 4014 to 4016, and thusconnect to external equipment.

A cover material 6000, a sealing material (also called a housingmaterial) 7000, and a sealant (a second sealing material) 7001 should beformed around at least the pixel portion at this point, and preferablyaround both the pixel portion and the drive circuits at this point.

In addition, FIG. 23B is the cross sectional structure of the EL displaydevice of embodiment 12. A driver circuit TFT 4022 (however, a CMOScircuit combining an n-channel type TFT and a p-channel type TFT isshown here) and a pixel TFT 4023 (however, only a TFT for controllingthe current to an EL element is shown here) are formed on the substrate4010 and a base film 4021. An example using a bottom gate type TFT, inaccordance with the manufacturing method shown in embodiment 9, is shownhere, but there are no particular limitations, and a known structure(top gate structure or bottom gate structure) may be used for the TFT.

After completing the driver circuit TFT 4022 and the pixel TFT 4023using the present invention, a pixel electrode 4027 is formed by atransparent conductive film, on an interlayer insulating film (aflattening film) 4026 which is formed of a resin material, in order toelectrically connect to the drain of the pixel TFT 4023. An indium oxideand tin oxide compound (called ITO), or an indium oxide and zinc oxidecompound can be used as the transparent conductive film. Then, afterforming the pixel electrode 4027, an insulating film 4028 is formed, andan open section is formed in the pixel electrode 4027.

An EL layer 4029 is formed next. Any known EL materials (hole injectionlayer, hole transport layer, illumination layer, electron transportlayer, electron injection layer) may be freely combined and used in alaminate structure or a single layer structure. A known technique may beused to determine the structure type. Further, there are low molecularweight materials and high molecular weight materials (polymers) as ELmaterials. An evaporation method is used for low molecular weightmaterials, but it is possible to use an easy method such as spincoating, printing, or injecting for high molecular weight materials.

The EL layer is formed in embodiment 12 by an evaporation method using ashadow mask. By using the shadow mask and forming a luminescence layerthat can emit different wavelengths of light for each pixel (red lightemitting layer, green light emitting layer, and blue light emittinglayer), color display is possible. Any other form may be used, such ascombining color changing layers (CCM) with color filters, and combiningwhite light emitting layers with color filters. Of course a single colorlight EL display device is also possible.

After forming the EL layer 4029, a cathode 4030 is formed on top. It ispreferable to remove as much as possible of the moisture and oxygenexisting in the interface between the cathode 4030 and the EL layer4029. Therefore, it is necessary to form the EL layer 4029 and thecathode 4030 inside a vacuum by successive film deposition, or to formthe EL layer 4029 in an inert atmosphere and then form the cathode 4030without exposure to the atmosphere. It is possible to perform the abovefilm deposition in embodiment 12 by using a multi-chamber system(cluster tool system) deposition device.

Note that a laminate structure of a LiF (lithium fluoride) film and anAl (aluminum) film is used for the cathode 4030 in embodiment 12.Specifically, a 1 nm thick LiF (lithium fluoride) film is formed on theEL layer 4029 by evaporation, and a 300 nm thick aluminum film is formedon top of that. Of course an MgAg electrode, a known cathode material,may be used. Then the cathode 4030 is connected to the wiring 4016 bythe region denoted with the reference numeral 4031. The wiring 4016 is apower supply line in order to apply a preset voltage to the cathode4030, and is connected to the FPC 4017 through a conductive pastematerial 4032.

The region denoted by reference numeral 4031 electrically connects thecathode 4030 and the wiring 4016, so it is necessary to form contactholes in the interlayer insulating film 4026 and the insulating film4028. The contact holes may be formed during etching of the interlayerinsulating film 4026 (when forming the pixel electrode contact hole) andduring etching of the insulating film 4028 (when forming the opensection before forming the EL layer). Further, etching may be proceededin one shot all the way to the interlayer insulating film 4026 whenetching the insulating film 4028. In this case the contact holes canhave a good shape provided that the interlayer insulating film 4026 andthe insulating film 4028 are the same resin material.

A passivation film 6003, a filling material 6004, and the cover material6000 are formed, covering the surface of the EL element thus formed.

In addition, a sealing material is formed on the inside of the covermaterial 6000 and the substrate 4010, so as to surround the EL elementsection, and the sealant 7001 (the second sealing material) is formed onthe outside of the sealing material 7000.

At this point the filling material 6004 also functions as an adhesive inorder to bond the cover material 6000. PVC (polyvinyl chloride), epoxyresin, silicon resin, PVB (polyvinyl butyral), and EVA (ethylene vinylacetate) can be used as the filling material 6004. If a drying agent isformed on the inside of the filling material 6004, a moisture absorptioneffect can be maintained, so this is preferable.

In addition, spacers may be included within the filling material 6004.The spacers may be a powdered substance such as BaO, etc., giving thespacers themselves the ability to absorb moisture.

When using spacers, the passivation film 6003 can relieve the spacerpressure. Further, a resin film, etc., can be formed separately from thepassivation film 6003 to relieve the spacer pressure.

Furthermore, a glass plate, an aluminum plate, a stainless steel plate,an FRP (fiberglass-reinforced plastic) plate, a PVF (polyvinyl fluoride)film, a Mylar film, a polyester film, and an acrylic film can be used asthe cover material 6000. Note that if PVB or EVA is used as the fillingmaterial 6004, it is preferable to use a sheet with a structure in whichseveral tens of μm of aluminum foil is sandwiched by a PVF film or aMylar film.

However, depending upon the light emission direction from the EL device(the light irradiation direction), it is necessary for the covermaterial 6000 to have light transmitting characteristics.

In addition, the wiring 4016 is electrically connected to the FPC 4017through the opening between the sealing material 7000, the sealant 7001,and the substrate 4010. Note that an explanation of the wiring 4016 hasbeen made, and the wirings 4014 and 4015 are also connected electricallyto the FPC 4017 by similarly passing underneath the sealing material7000 and the sealant 7001.

In addition, the pixel electrode is used as an anode in embodiment 12,so it is preferable to use a PTFT for the current control TFT.Embodiment 9 may be referred to for the manufacturing process. The lightemitted by the light emitting layer is irradiated toward the substrateon which the TFT is formed in embodiment 12. In addition, the NTFT ofthe present invention may also be used to form the current control TFT.When using an NTFT as the current control TFT, a pixel electrode (ELelement cathode) which is formed of a high reflectivity conductive filmmay connected to the drain of the pixel portion TFT 4023, and an ELlayer, and a conductive film having light transparency characteristicswhich forms an anode may be manufactured in order. In this case, thelight generated from the light emitting layer is irradiated toward thesubstrate on which the TFT is not formed.

Note that the present invention may be realized by freely combining anyof the embodiments 1 to 11.

Embodiment 13

A CMOS circuit and a pixel matrix unit formed through carrying out thepresent invention may be applied to various electro-optical devices(active matrix type liquid crystal displays, active matrix type ELdisplays, active matrix type EC displays). Namely, the present inventionmay be carried out in all the electronic equipments that incorporatethose electro-optical devices into display units.

As such an electronic equipment, a video camera, a digital camera, aprojector (a rear-type or a front-type projector), a head mount display(a goggle-type display), a navigation system for vehicles, a personalcomputer, and a portable information terminal (a mobile computer, acellular phone, or an electronic book, etc.) may be enumerated. Examplesof those are shown in FIGS. 21A to 21F, 24A to 24D and 25A to 25C.

FIG. 21A shows a personal computer comprising a main body 2001, an imageinputting unit 2002, a display unit 2003, and a key board 2004 and thelike. The present invention is applicable to the image inputting unit2002, the display unit 2003, and other signal control circuits.

FIG. 21B shows a video camera comprising a main body 2101, a displayunit 2102, a voice input unit 2103, operation switches 2104, a battery2105, and an image receiving unit 2106 and the like. The presentinvention is applicable to the display unit 2102 and other signalcontrol circuits.

FIG. 21C shows a mobile computer comprising a main body 2201, a cameraunit 2202, an image receiving unit 2203, an operation switch 2204, and adisplay unit 2205 and the like. The present invention is applicable tothe display unit 2205 and other signal control circuits.

FIG. 21D shows a part (right one side) of a head attachment type ELdisplay comprising a main body 2301, a signal cable 2302, a head fixingband 2303, a display unit 2304, an optical system 2305 and a displaydevice 2306 and the like. The present invention is applicable to thedisplay device 2306.

FIG. 21E shows a player that employs a recoding medium in which programsare recorded (hereinafter referred to as recording medium), andcomprises a main body 2401, a display unit 2402, a speaker unit 2403, arecording medium 2404, and an operation switch 2405 and the like. Notethat this player uses as the recoding medium a DVD (digital versatiledisc), a CD and the like to serve as a tool for enjoying music ormovies, for playing video games and for connecting to the Internet. Thepresent invention is applicable to the display unit 2402 and othersignal control circuits.

FIG. 21F shows a digital camera comprising a main body 2501, a displayunit 2502, an eye piece section 2503, operation switches 2504, and animage receiving unit (not shown) and the like. The present invention isapplicable to the display unit 2502 and other signal control circuits.

FIG. 24A shows a front-type projector comprising a projection device2601, a screen 2602 and the like. The present invention is applicable toa liquid crystal display device 2808 that constitutes a part of theprojection device 2601 and other signal control circuits.

FIG. 24B shows a rear-type projector comprising a main body 2701, aprojection device 2702, a mirror 2703, and a screen 2704 and the like.The present invention is applicable to the liquid crystal display device2808 that constitutes a part of the projection device 2702 and othersignal control circuits.

FIG. 24C is a diagram showing an example of the structure of theprojection devices 2601 and 2702 in FIGS. 24A and 24B. The projectiondevice 2601 or 2702 comprises a light source optical system 2801,mirrors 2802 and 2804 to 2806, dichroic mirrors 2803, a prism 2807,liquid crystal display devices 2808, phase difference plates 2809, and aprojection optical system 2810. The projection optical system 2810consists of an optical system including a projection lens. Thisembodiment shows an example of “three plate type”, but not particularlylimited thereto. For instance, the invention may be applied also to a“single plate type”. Further, in the light path indicated by an arrow inFIG. 24C, an optical system such as an optical lens, a film having apolarization function, a film for adjusting a phase difference and an IRfilm may be provided on discretion of a person who carries out theinvention.

FIG. 24D is a diagram showing an example of the structure of the lightsource optical system 2801 in FIG. 24C. In this embodiment, the lightsource optical system 2801 comprises a reflector 2811, light source2812, lens arrays 2813 and 2814, a polarization conversion element 2815,and a condenser lens 2816. Note that the light source optical systemshown in FIG. 24D is an example thereof, and is not particularly limitedthereto. For instance, on discretion of a person who carries out theinvention, the light source optical system may be provided with anoptical system such as an optical lens, a film having a polarizationfunction, a film for adjusting the phase difference and an IR film.

The projectors shown in FIGS. 24A–24D show the case in which theelectric optical device of a transmission type is employed and anapplication example using the electric optical device of reflection typeand the EL display device is not illustrated.

FIG. 25A is a cellular phone that is composed of a main body 2901, avoice output unit 2902, a voice input unit 2903, a display unit 2904,operation switches 2905, and an antenna 2906 and the like. The presentinvention can be applied to the voice output unit 2902, the voice inputunit 2903 and the display unit 2904 and other signal control circuits.

FIG. 25B shows a portable book (electronic book) that is comprised of amain body 3001, display units 3002 and 3003, a memory medium 3004, anoperation switch 3005 and an antenna 3006 and the like. The presentinvention can be applied to the display units 3002 and 3003 and to othersignal circuits.

FIG. 25C shows a display that is comprised of a main body 3101, asupport base 3102 and a display unit 3103 and the like. The presentinvention can be applied to the display unit 3103. The display accordingto the present invention is advantageous in the case where the displayis particularly large-sized and in the case where the display is 10inches or more in an opposite angle (particularly 30 inches or more).

As described above, the present invention has so wide application rangethat it is applicable to electronic equipments in any field. Inaddition, the electronic equipments of this embodiment may be realizedwith any construction obtained by combining Embodiments 1 through 12.

According to the present invention, the uniformity in the surface thatis the effect of laser annealing by the laser beam may be improved.

1. A method of irradiating with a laser, said method comprising thesteps of: providing a glass substrate having a non-single semiconductorfilm formed over the glass substrate with an insulating film interposedtherebetween; irradiating the non-single semiconductor film with thelaser, wherein an output power Lw (W) of the laser and a spot size Sp(cm²) on an irradiated surface satisfy the following relationships,Lw>1×10⁵ Sp, andSp>2.5×10⁻⁵.
 2. A method of irradiating with a laser, said methodcomprising the steps of: providing a glass substrate having a non-singlesemiconductor film formed over the glass substrate with an insulatingfilm interposed therebetween; irradiating the non-single semiconductorfilm with the laser, wherein an output power Lw (W) of the laser and aspot size Sp (cm²) on an irradiated surface satisfy the followingrelationships,Lw>2×10⁵ Sp, andSp>2.5×10⁻⁵.
 3. A method of irradiating with a laser, said methodcomprising the steps of: providing a glass substrate having a non-singlesemiconductor film formed over the glass substrate with an insulatingfilm interposed therebetween; irradiating the non-single semiconductorfilm with the laser, wherein an output power Lw (W) of the laser and aspot size Sp (cm²) on an irradiated surface satisfy the followingrelationships,Lw>2×10³ Sp, andSp>2.5×10⁻⁵.
 4. A method according to claim 1, wherein a spot shape ofthe laser on the irradiated surface is processed into a linear shape byan optical system.
 5. A method according claim 1, wherein an energyfluctuation of the laser is within ±10% during irradiating onesubstrate.
 6. A method according to claim 1, wherein an energyfluctuation of the laser is within ±3% during irradiating one substrate.7. A method according to claim 1, wherein an energy fluctuation of thelaser is within ±1% during irradiating one substrate.
 8. A method ofirradiating with a laser having a linear shape on an irradiated surface,said method comprising the steps of: providing a glass substrate havinga non-single semiconductor film formed over the glass substrate with aninsulating film interposed therebetween; irradiating the non-singlesemiconductor film with the laser having the linear shape, wherein anoutput power Lw (W) of the laser and a spot size Sp (cm²) on theirradiated surface satisfy the following relationships,Lw>1×10⁵ Sp, andSp>2.5×10⁻⁵.
 9. A method of irradiating with a laser having a linearshape on an irradiated surface, said method comprising the steps of:providing a glass substrate having a non-single semiconductor filmformed over the glass substrate with an insulating film interposedtherebetween; irradiating the non-single semiconductor film with thelaser having the linear shape, wherein an output power Lw (W) of thelaser and a spot size Sp (cm²) on the irradiated surface satisfy thefollowing relationships,Lw>2×10⁵ Sp, andSp>2.5×10⁻⁵.
 10. A method of irradiating with a laser having a linearshape on an irradiated surface, said method comprising the steps of:providing a glass substrate having a non-single semiconductor filmformed over the glass substrate with an insulating film interposedtherebetween; irradiating the non-single semiconductor film with thelaser having the linear shape, wherein an output power Lw (W) of thelaser and a spot size Sp (cm²) on the irradiated surface satisfy thefollowing relationships,Lw>2×10³ Sp, andSp>2.5×10⁻⁵.
 11. A method according to claim 8, wherein an energydistribution of the laser is within ±5% in a linear direction.
 12. Amethod according to claim 8, wherein an energy distribution of the laseris within ±3% in a linear direction.
 13. A method according to claim 8,wherein an energy distribution of the laser is within ±1% in a lineardirection.
 14. A method according to claim 2, wherein a spot shape ofthe laser on the irradiated surface is processed into a linear shape byan optical system.
 15. A method according claim 2, wherein an energyfluctuation of the laser is within ±10% during irradiating onesubstrate.
 16. A method according to claim 2, wherein an energyfluctuation of the laser is within ±3% during irradiating one substrate.17. A method according to claim 2, wherein an energy fluctuation of thelaser is within ±1% during irradiating one substrate.
 18. A methodaccording to claim 3, wherein a spot shape of the laser on theirradiated surface is processed into a linear shape by an opticalsystem.
 19. A method according claim 3, wherein an energy fluctuation ofthe laser is within ±10% during irradiating one substrate.
 20. A methodaccording to claim 3, wherein an energy fluctuation of the laser iswithin ±3% during irradiating one substrate.
 21. A method according toclaim 3, wherein an energy fluctuation of the laser is within ±1% duringirradiating one substrate.
 22. A method according to claim 9, wherein anenergy distribution of the laser is within ±5% in a linear direction.23. A method according to claim 9, wherein an energy distribution of thelaser is within ±3% in a linear direction.
 24. A method according toclaim 9, wherein an energy distribution of the laser is within ±1% in alinear direction.
 25. A method according to claim 10, wherein an energydistribution of the laser is within ±5% in a linear direction.
 26. Amethod according to claim 10, wherein an energy distribution of thelaser is within ±3% in a linear direction.
 27. A method according toclaim 10, wherein an energy distribution of the laser is within ±1% in alinear direction.
 28. A method of manufacturing a semiconductor devicecomprising: forming a semiconductor film on an insulating surface;irradiating the semiconductor film with a laser to crystallize saidsemiconductor film, wherein an output power Lw (W) of the laser and aspot size Sp (cm²) on an irradiated surface satisfy the followingrelationships,Lw>1×10⁵ Sp, andSp>2.5×10⁻⁵.
 29. A method according to claim 28 wherein said laser is anexcimer laser.